The sympathetic adrenomedullary system, but not the hypothalamic-pituitary-adrenal axis, participates in aorta adaptive response to stress: nitric oxide involvement

Stress induced a decrease in the reactivity of the aorta to noradrenaline (NA), as a consequence of an endothelial nitric oxide (NO) system hyperactivity. The main characteristic of the stress response is activation of the hypothalamic-pituitary-adrenal (HPA) axis and sympathetic adrenomedullary (SA) system. The participation of the HPA axis and SA system in the decreased reactivity to NA in the aorta of rats exposed to 4-h immobilization was investigated. Concentration-response relationships for NA were obtained in the aorta, with and without endothelium, isolated from normal and stressed rats, following these procedures: (1) in the absence and presence of L-NAME; (2) after adrenalectomy (ADX) or not, in the absence or presence of L-NAME; (3) ADX rats treated or not with corticosterone; (4) ADX associated with stress; and (5) treated or not with reserpine. The reactivity of aorta without endothelium was unaffected by the procedures. The reactivity of aorta with endothelium was decreased by either stress or ADX. This effect was reversed by both L-NAME and corticosterone. ADX did not potentiate the decrease in the aorta reactivity induced by stress. Reserpine did not change the reactivity of aorta with endothelium from normal rats, but prevented the decrease in reactivity induced by stress. It is concluded that the HPA axis participates in endothelium-dependent modulation of aorta reactivity in normal conditions and that thr SA system participates in hyperactivity of the endothelial NO-system induced by stress, which is responsible for the decreased aorta reactivity to NA. (C) 2000 Elsevier B.V. B.V. All rights reserved.

On the taxonomic value of the anatomical structure of vegetative organs and inflorescence axis of Abolboda species (Xyridaceae - Poales)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Non-ventilation during early incubation in combination with dexamethasone administration during late incubation: 1. Effects on physiological hormone levels, incubation duration and hatching events

This study investigated the effect of non-ventilation of the incubator during the first 10 days of incubation and its combination with dexamethasone administration at day 16 or 18 of incubation on hatching parameters and embryo and post-hatch chick juvenile physiology. A total of 2400 hatching eggs produced by Cobb broiler breeders were used for the study. Blood samples were collected at day 18 of incubation, at internal pipping stage (IP), at the end of hatch (day-old chick) and at 7-daypost-hatch for T-3, T-4 and corticosterone levels determination. From 448 to 506 h of incubation, the eggs were checked individually in the hatcher every 2 h for pipping and hatching. The results indicate that non-ventilation during the first 10-day shortened incubation duration up to IP, external pipping (EP) and hatch, had no effect on hatchability and led to higher T-3 levels at IP but lower corticosterone levels at 7-day-post-hatch. The injection of dexamethasone at days 16 and 18 of incubation affected hatching and blood parameters in both the ventilated and non-ventilated embryos differentially and the effect was dependent on the age of the embryo. Dexamethasone increased T-3 levels and T-3/T-4 ratios but the effect was greater with early non-ventilation of eggs. Dexamethasone decreased hatchability but the effect was greater when injected at day 16 and especially in ventilated embryos. The effects of incubation protocols and dexamethasone treatments during incubation were still apparent in the hatched chicks until 7 days of age. The changes in T-3, T-4 and corticosterone levels observed in response to the early incubation conditions and late dexamethasone treatments in this study suggest that incubator ventilation or non-ventilation may influence the hypothalamic-pituitary-adrenal axis (HPA) regulation of stress levels (in terms of plasma corticosterone levels) and thyroid function in the embryo with impact on incubation duration, hatching events and early post-hatch life of the chick. Our results also suggest that some stages of development are more sensitive to dexamethasone administration as effects can be influenced by early incubation protocols. (c) 2006 Elsevier B.V. All rights reserved.

Pressure field along the axis of a high-power klystron amplifier

The pressure field in a high-power klystron amplifier is investigated to scale the ionic vacuum pump used to maintain the ultra high-vacuum in the device in order to increase its life-time. The investigation is conducted using an 1.3 GHz, 100 A - 240 keV high-power klystron with five reentrant coaxial cavities, assembled in a cylindrical drift tube 1.2 m long. The diffusion equation is solved to the regime molecular flow to obtain the pressure profile along the axis of the klystron drift tube. The model, solved by both analytical and numerical procedures, is able to determine the pressure values in steady-state case. This work considers the specific conductance and all important gas sources, as in the degassing of the drift tube and cavities walls, cathode, and collector. For the drift tube degassing rate equals to q(deg) = 2x10(-12) (-)mbar.L.s(-1) cm(-2) (degassing rate per unit area), to cavities q(cavity) = 3x10(-13) mbar.L.s(-1)cm(-2), to the cathode q(cathode) = 6x10(-9)_mbar.L.s(-1) and to the collector q(collector) = 6x10(-9) mbar.L.s(-1), it was found that a 10 L.s(-1) ionic vacuum pump connected in the output waveguide wall is suitable. In this case, the pressure obtained in the cathode is p(cathode) = 6.3x10(-9) mbar, in the collector p(collector) = 2.7x10(-9) mbar, and in the output waveguide p = 2.1x10(-9) mbar. Although only the steady-state case is analyzed, some aspects that may be relevant in a transient situation, for instance, when the beam hits the drift tube walls, producing a gas burst, is also commented.

a-b axis-oriented lanthanum doped Bi4Ti3O12 thin films grown on a TiO2 buffer layer

a-b axis-oriented, lanthanum doped Bi4Ti3O12 (BLT) thin films with a TiO2 rutile buffer layer deposited on Pt/Ti/SiO2/Si substrates were grown by the soft chemical method. Butterfly dielectric behavior has been achieved and can be ascribed to the ferroelectric domain switching. The remanent polarization and the coercive voltage for the film deposited on TiO2 buffer layer were 22.2 mu C/cm(2) and 1.8 V, respectively. Random-oriented BLT films showed a reduction in switching polarization when compared to the a-b axis-oriented films. Due to the excellent physical properties, these films are a promising candidate for use in lead-free applications in ferroelectric devices. (c) 2006 American Institute of Physics.

Effects of Short-term Hyper- and Hypoprolactinaemia on Hormones of the Pituitary, Gonad and -Thyroid Axis and on Semen Quality in Male Beagles

Effects of a short-term hyper- and hypoprolactinaemia on serum concentrations of LH, testosterone and semen quality in six male Beagles were investigated. Blood samples were collected at 3-day intervals for 12 weeks. The time span was divided into five 3-week periods: pre-treatment, metoclopramide (MCP) treatment (0.2 mg/kg orally three times daily), cabergoline (CAB) treatment (5 mu g/kg orally once daily), post-treatment 1 and post-treatment 2. In the latter, only semen characteristics were evaluated. Semen parameters were analyzed once per week during the whole 15-week investigation time. At the end of each period, the effects of a single intravenous injection of thyrotropin-releasing hormone (TRH; 10 mu g/kg) on the secretion of prolactin (PRL), LH, testosterone, thyroid-stimulating hormone and thyroxine (T4) were investigated. Pre-treatment serum PRL concentration increased under MCP (p < 0.05), followed by a decrease under CAB administration (p < 0.05). Luteinizing hormone and testosterone concentrations were not affected. Except for straight-line sperm velocity, semen quality did not differ between collection periods. A single iv TRH injection induced a significant PRL increase at 20 min in all experimental periods except during CAB treatment. Luteinizing hormone and testosterone did not show clear TRH-related changes. Basic T4 levels were significantly reduced after CAB treatment ( p < 0.05). The results of the present study demonstrate that MCP-induced short-term hyperprolactinaemia in male beagles does not seriously affect the hypothalamo-pituitary axis and semen quality.

Exigências de proteína para frangas de postura de 1 a 18 semanas de idade

The objective of this experiment was to determine the protein requirements for hen pullets from 1 to 18 weeks of age, by factorial method, using the nitrogen balance and the comparative slaughtering techniques. Protein requirements for maintenance, was obtained by the nitrogen balance technique using four diets with different protein levels (18,9, 4 and 2% of CP) aiming to obtain positive balance, next to zero and negative nitrogen balance. The endogenous nitrogen losses (0.2575 g of N/kg·75/day) was obtained by regression of nitrogen balance (NB) on ingestion nitrogen (IN). The requirements of nitrogen for maintenance was estimated by the intercept of axis X (0.3831 g of N/kg·75/day). The slope of the straight line still supplied the efficiency of N of the diet (67.21%). The regression coefficients of the equation represented the requirements of net nitrogen for weight gain. Considering the conversion efficiencies of nitrogen of the diet into nitrogen for weight gain, the requirements of nitrogen were determined for weight gain of .065, .087g and .090 g of N per gram of weight gain, for the phases 1 to 6, 7 to 12, and 13 to 18 weeks of age, respectively. Based on the results, three equations of prediction of the daily nitrogen requirements were fitted in function of live weight (LW in kg) and daily weight gain (G in g): 1 to 6 weeks N=.3831 x BW·75 + G .065, 7 to 12 weeks N=.3831 × BW·75 + G .087, and 13 to 18 weeks N=.3831 × BW·75 + G .090.

Structure of tick anticoagulant peptide at 1.6 Å resolution complexed with bovine pancreatic trypsin inhibitor

The structure of tick anticoagulant peptide (TAP) has been determined by X-ray crystallography at t.6 Å resolution complexed with bovine pancreatic trypsin inhibitor (BPTI). The TAP-BPTI crystals are tetragonal, a = b = 46.87, c = 50.35 Å, space group P41, four complexes per unit cell. The TAP molecules are highly dipolar and form an intermolecular helical array along the c-axis with a diameter of about 45 Å. Individual TAP units interact in a head-to-tail fashion, the positive end of one molecule associating with the distal negative end of another, and vice versa. The BPTI molecules have a uniformly distributed positively charged surface that interacts extensively through 14 hydrogen bonds and two hydrogen bonded salt bridges with the helical groove around the helical TAP chains. Comparing the structure of TAP in TAP-BPTI with TAP bound to factor Xa(Xa) suggests a massive reorganization in the N-terminal tetrapeptide and the first disulfide loop of TAP (CyS5(T)- Cys 15(T)) upon binding to Xa. The Tyr1(T)OH atom of TAP moves 14.2 Å to interact with Asp189 of the S1 specificity site, Arg3(T)CZ moves 5.0 Å with the guanidinium group forming a cation-π-electron complex in the S4 subsite of Xa, while Lys7(T)NZ differs in position by 10.6 Å in TAP-BPTI and TAP-Xa, all of which indicates a different pre-Xa-bound conformation for the N- terminal of TAP in its native state. In contrast to TAP, the BPTI structure of TAP-BPTI is practically the same as all those of previously determined structures of BPTI, only arginine and lysine side-chain conformations showing significant differences.

Search for resonant pair production of neutral long-lived particles decaying to bb̄ in pp̄ collisions at s=1.96TeV

We report on a first search for resonant pair production of neutral long-lived particles (NLLP) which each decay to a bb̄ pair, using 3.6fb-1 of data recorded with the D0 detector at the Fermilab Tevatron collider. We search for pairs of displaced vertices in the tracking detector at radii in the range 1.6-20cm from the beam axis. No significant excess is observed above background, and upper limits are set on the production rate in a hidden-valley benchmark model for a range of Higgs boson masses and NLLP masses and lifetimes. © 2009 The American Physical Society.

Evaluation of the hypothalamus-pituitary axis response to exogenous GnRH, estradiol benzoate, And LH during the postpartum period in Nellore cows

The objective was to evaluate when the LH reserve was re-established in postpartum Nellore (Bos indicus) cows by evaluating the response of the hypothalamic-pituitary axis responsiveness to exogenous GnRH or estradiol benzoate (EB). Additionally, we tested the influence of dietary supplementation (SUPL) and calf removal (CR) on the duration of postpartum anestrus. Ninety multiparous lactating Nellore cows were randomly assigned to eight groups. The EB and GnRH groups received 1.0 mg EB (N = 7), and 50 μg lecireline (N = 16), respectively. Additional cows were given the same hormones, and subjected to either nutritional supplementation (EB-SUPL, N = 9; GnRH-SUPL, N = 16), or calf removal at 72 hours after calving (EB-CR, N = 4; GnRH-CR, N = 13). The remaining two groups were the LH (12.5 mg, N = 14) and control groups (saline, N = 11). Hormones were administered weekly from 7 (±5) days postpartum to first ovulation (detection of a CL during a weekly ultrasonographic examination). Blood samples were collected just before and 2 hours (GnRH, LH, and control groups) or 18 hours (EB groups) after hormone or saline (control) administration. Ovulation occurred as early as 15 days postpartum in the GnRH group. The mean ± SEM intervals (days) from calving to first ovulation were EB, 87.7 ± 4.2; EB-CR, 20.3 ± 1.2; EB-SUPL, 60.3 ± 3.2; GnRH, 40.4 ± 2.1; GnRH-CR, 21.0 ± 1.1; GnRH-SUPL, 26.4 ± 1.1; LH, 35.6 ± 1.1; and control, 60.9 ± 2.1. We concluded that there was sufficient LH in the pituitary gland (of Nellore cows) from the second week postpartum to induce ovulation in response to exogenous GnRH. Additionally, calf removal and nutritional supplementation reduced, by 2 to 4 weeks, the interval from calving to an LH increase and ovulation induced by GnRH or EB. © 2013.

Práticas de leitura: concepção de uma docente da 1 ª série do ensino fundamental da cidade de Umuarama-PR

Pós-graduação em Educação - FFC

Treinamento físico aeróbio e o eixo de crescimento GH/IGF-1 em ratos diabéticos experimentais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Polymorphism analysis in genes of the somatotropic axis in Nellore cattle selected for growth

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)